ios - 获取相对于 SKEffectNode 屏幕的绝对位置，因为它被 SKWarpGeometryGrid 扭曲

Question

我有一个 SKVideoNode 作为 SKEffectNode 的子节点，这使我能够使用 1 行 x 1 列的 SKWarpGeometryGrid 来倾斜视频。

当您在每个象限中拖动手指时，在 touchMoved(toPoint fingerPos: CGPoint) 中计算新的角坐标，然后在 updateGrid() 中更新 SKWarpGeometryGrid

我还有一个以 SKView 为中心的蓝色方 block (因此位于视频的初始中心)。当 effectNode 扭曲时，我希望蓝色方 block 跟随 videoNode 的中心。我不希望将正方形作为子级添加到 effectNode，因为正方形也会变形。

我尝试了 convert(:to:) 和 convert(:from:) 的各种参数排列

例如

blueSquare?.position = self.convert(effectNode!.position, to: self)

……但是蓝色方 block 永远不会移动。有什么想法吗？

代码:(用视频文件替换myFriend.mp4进行测试)

import SpriteKit
import GameplayKit

class GameScene: SKScene {

let warpGeometryGrid1Col = SKWarpGeometryGrid(columns: 1,rows: 1)

var warpGridPositions: [float2] = [
float2(0.0, 0.0),  float2(1.0, 0.0),
float2(0.0, 1.0),  float2(1.0, 1.0)]
var adjust: Float = 0.005
var previousPosX: CGFloat = 0
var previousPosY: CGFloat = 0
var topLeftX:Float = 0.0
var topLeftY:Float = 1.0
var topRightX:Float = 1.0
var topRightY:Float = 1.0
var bottomLeftX:Float = 0.0
var bottomLeftY:Float = 0.0
var bottomRightX:Float = 1.0
var bottomRightY:Float = 0.0

var blueSquare:SKSpriteNode?
var effectNode: SKEffectNode?

override func didMove(to view: SKView) {

// **** add a video file to the project
  let videoNode = SKVideoNode.init(fileNamed: "myFriend.mp4")
videoNode.size.width = self.frame.size.height/3*1.5
videoNode.size.height = self.frame.size.width/3*1.5
videoNode.play()

effectNode = SKEffectNode()
effectNode!.addChild(videoNode)
self.addChild(effectNode!)

blueSquare = SKSpriteNode.init(color: .blue, size: CGSize(width: 50, height: 50))
self.addChild(blueSquare!)
}

func updateGrid(){
warpGridPositions = [float2(bottomLeftX, bottomLeftY), float2(bottomRightX, bottomRightY),
                     float2(topLeftX, topLeftY), float2(topRightX, topRightY)]
effectNode!.warpGeometry = warpGeometryGrid1Col.replacingByDestinationPositions(positions: warpGridPositions)

//*********************************
//*********************************
// TRY TO ADJUST POSITION OF blueSquare AS EFFECT 
// NODE IS WARPED KEEPING IT CENTERED ON THE 
// EFFECT NODE'S CHILD VIDEO
blueSquare?.position = self.convert(effectNode!.position, to: self)
//*********************************
//*********************************
}

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
for t in touches { self.touchMoved(toPoint: t.location(in: self)) }
}

func touchMoved(toPoint fingerPos : CGPoint) {
if fingerPos.y < 0{
  if fingerPos.x > 0{// bottom right
    if fingerPos.x > previousPosX {
      bottomRightX += adjust
    }
    if fingerPos.x < previousPosX {
      bottomRightX -= adjust
    }
    if fingerPos.y > previousPosY {
      bottomRightY += adjust
    }
    if fingerPos.y < previousPosY {
      bottomRightY -= adjust
    }
  }
  else{ // bottom left
    if fingerPos.x > previousPosX {
      bottomLeftX += adjust
    }
    if fingerPos.x < previousPosX {
      bottomLeftX -= adjust
    }
    if fingerPos.y > previousPosY {
      bottomLeftY += adjust
    }
    if fingerPos.y < previousPosY {
      bottomLeftY -= adjust
    }
  }
} else{
  // top right
  if fingerPos.x > 0{
    if fingerPos.x > previousPosX {
      topRightX += adjust
    }
    if fingerPos.x < previousPosX {
      topRightX -= adjust
    }
    if fingerPos.y > previousPosY {
      topRightY += adjust
    }
    if fingerPos.y < previousPosY {
      topRightY -= adjust
    }
  }
  else{ // top left
    if fingerPos.x > previousPosX {
      topLeftX += adjust
    }
    if fingerPos.x < previousPosX {
      topLeftX -= adjust
    }
    if fingerPos.y > previousPosY {
      topLeftY += adjust
    }
    if fingerPos.y < previousPosY {
      topLeftY -= adjust
    }
  }
}

updateGrid()
previousPosX = fingerPos.x
previousPosY = fingerPos.y
}


}

Answer 1

如果effectNode是从SKScene的中心开始，直接计算。可以缓存 viewFrame 以加速计算。

   var videoFrame : CGRect!
        override func didMove(to view: SKView) {

            // **** add a video file to the project
            let videoNode = SKVideoNode.init(fileNamed: "myFriend.mp4")
            videoNode.size.width = self.frame.size.height/3*1.5
            videoNode.size.height = self.frame.size.width/3*1.5
            videoNode.play()
            videoFrame =  (videoNode.frame)

        effectNode = SKEffectNode()
        effectNode!.addChild(videoNode)

        self.addChild(effectNode!)

        blueSquare = SKSpriteNode.init(color: .blue, size: CGSize(width: 50, height: 50))
        self.addChild(blueSquare!)
    }

    func updateGrid(){
        warpGridPositions = [float2(bottomLeftX, bottomLeftY), float2(bottomRightX, bottomRightY),
                             float2(topLeftX, topLeftY), float2(topRightX, topRightY)]
        effectNode!.warpGeometry = warpGeometryGrid1Col.replacingByDestinationPositions(positions: warpGridPositions)
         let finalRatio =  ( warpGridPositions.reduce(float2(),+) / 4.0)
         let   finalWidth = videoFrame.origin.x + CGFloat(finalRatio.x) * videoFrame.size.width
         let   finalHeight = videoFrame.origin.y + CGFloat(finalRatio.y) * videoFrame.size.height
         blueSquare?.position = CGPoint.init(x:finalWidth , y: finalHeight)

    }

希望没有问题